This invention relates to guide trays and more particularly to a guide tray capable of supporting and constraining flexible tubing.
A number of industries, such as the food processing and pharmaceutical industries, have traditionally used stainless steel tubing or piping for the transfer of fluid materials in various processes. In such processes the temperature of the fluid conveyed by the tubing may vary dramatically often in excess of 100.degree. C. Particularly, in sanitary systems cleaning of tubing systems is accomplished with steam. Moreover, in such processes the tubing lines are ideally positioned to allow free draining of the lines. That is, positioned at an incline without low undrainable collection areas. With stainless steel tubing expansion and contraction of the tubing was minimal and could easily be accommodated by the tubing. Moreover, the rigidity and strength of stainless steel tubing allowed extended runs at an incline using intermittent supports without creating low hanging, non-drainable areas. Use of stainless has some problems including cost, difficulty in fabrication and susceptibility to corrosion in some sanitary applications.
Plastic tubing and fittings have become more prevalent in sanitary systems due to many advantages including cost, ease of assembly, and resistance to corrosion. However, plastic tubing is substantially more flexible than stainless and is much more susceptible to expansion and contraction due to temperature changes. A ten-foot length of plastic tubing can change in length by almost an inch which is approximately one hundred times greater than stainless. Tubing that has been pulled taught during installation will expand and contract and can cause extreme stress on the tube fittings eventually causing them to fail. Tubing that has been installed with a certain amount of slack will also experience the expansion as well as snaking. Uncontrolled snaking can also cause extreme stress on the tube fittings creating a potential for failure.
As a solution to these problems, various installations now incorporate large amounts of slack, e.g. u-shaped sections of tubing to accommodate the changes in tubing length due to temperature changes. These u-shaped sections of tubing do help to reduce the amount of pressure placed on tube fittings by expansion and snaking, however, new problems are introduced. Most importantly, obvious draining problems result. Moreover, additional amounts of tubing create additional expense. Further, the u-shaped sections take up valuable space that might otherwise be dedicated to additional fluid transfer lines. Moreover, numerous u-shaped sections will cause pressure losses throughout the length of the line which may create problems for the machinery the tubing is feeding.
In order to accommodate the inherent flexibility or lack of rigidity, long runs of tubing either need a radical incline or must incorporate numerous tubing supports in order to avoid low dangling, non-draining sections.
As well, sanitary tubing, piping, hoses, and associated connectors used in the food processing and pharmaceutical industries must meet sanitary requirements such as those set forth in the United States Code of Federal Regulations, 7 C.F.R. .sctn.58.128. The standards provide that the conduit be smooth, permit laminar flow of fluids and be free of discontinuities that could trap particulate matter. The fluid path must also be free of crevices that could give rise to capillary action that might allow the fluid being transported to accumulate and possibly putrefy. The addition of u-shaped tubing sections only multiplies the possibility of unwanted discontinuities and crevices.
In light of the above, there is a need for a guide tray that will eliminate the necessity of u-shaped sections and the problems associated with them, that will support the flexible tubing, that will constrain the amount of snaking by the tubing, that will significantly reduce the amount of stress placed on the tube fittings and further, that will be variable in length and configuration such that the guide tray may be adjusted to the length and configuration of the tubing run.